Recycling Cu(II) from complexing copper wastewater using ferrous sulfide stabilized by carboxymethyl cellulose: efficiency and mechanism insights

Abstract

Investigating the Cu(II) recovery rate in complexing copper wastewater holds significant importance in achieving resource recycling and enhancing the sustainability of industrial processes. In this study, the ferrous sulfide stabilized by carboxymethyl cellulose (CMC-FeS) was synthesized as a promising strategy to treat complexing copper wastewater, which addressed issues of the stability of FeS nanoparticles and recycling Cu(II) from complexing copper wastewater. Experimentally, the Cu(II) recovery rate was found to be 99.8 % from cupric tartrate (Cu-TA) solutions (Cu(II) = 640 mg/L), as well as the Cu(II) recovery rate reached up to 99.9 % from micro-etching copper-containing wastewater (Cu(II) = 6276.65 mg/L), when treated by CMC-FeS with the molar ratio of [FeS]/[Cu] = 1.25. The underlying mechanism has been systematically elucidated through chemical equilibriums, FTIR/Raman spectral analysis, SEM-EDS analysis, and XPS analysis, providing a solid foundation for further development and application. CMC-FeS can effectively compete with Cu(II) ligands to recover Cu(II) from copper complex wastewater, which is an efficient countermeasure for the treatment of copper complex wastewater. This process involves a variety of mechanisms, such as sulfide precipitation, replacement or ion exchange, complex adsorption, and flocculating sedimentation, finally produces insoluble precipitates with CuS as the main component. This study provides a valuable reference for the treatment of heavy metal complex wastewater, especially the recycling and utilizing metal resources.